A. Field of the Invention
The present invention relates to digital imaging, and in particular to repetitive duplication of an image area digitally stored in a display list.
B. Description of the Related Art
Computer storage and processing of images requires decomposition of image information into digital form. In high-level applications, such as pre-press or computer-aided design (CAD) systems, images are often represented and stored as specifications in a common representational format, e.g., page-description language instructions. Such a format reduces storage requirements and allows resolution-independent specification of image components.
In order to be output on a specific device, however, or in the case of complex images that cannot be represented by a series of instructions, image data must take the form of a raster pattern of discrete picture elements, or "pixels," with each pixel corresponding to an identified image point. The entire set of pixels representing an image is termed a "pixelmap" of the image. While simple monochrome image pixels can consist of single computer-memory bits, each of which indicates whether the corresponding image point is light or dark, color image pixels require additional specification information (e.g., values for hue, color value, and saturation). As used herein, the term "pixelmap" refers to raster patterns of pixels and/or bits.
In many areas of design, particularly those involving decorative applications, patterns may be based on repeating units which collectively form the complete image. Indeed, textile designers frequently devote the bulk of their creative efforts toward the origination of new unit cells, which are used as motifs in the construction of a variety of final image arrangements.
Unfortunately, current CAD systems do not provide the ability to selectively repeat defined image patterns throughout a pixelmap. Instead, users copy image portions manually to create a composite picture. This process is time-consuming and inconvenient. Depending on the manner in which copying is carried out, unintentional overwriting of image components can also occur.